The present invention relates to apparatus for forming a sealed joint between juxtaposed ends of two axially aligned pipes and particularly to apparatus of such type adapted for use with a sealing gasket in forming such a joint.
Broadly defined for purposes of herein describing the present invention, a pipe joint of the form to which the present invention is directed is one in which the ends of two pipes are sealably joined by apparatus disposed about each pipe end and acting to compress therebetween a resilient annular sealing gasket. Characteristically, apparatus for forming joints of this form comprise annular flange members adapted to be disposed in facing relationship about respective ones of the pipe ends with a sealing gasket therebetween and to be tightly joined as by a bolting arrangement or the like to seal the two pipe ends. Several types of such apparatus are in conventional use. One type of apparatus provides flange members having central threaded holes for threaded joinder about the respective pipe ends. Another conventional apparatus for forming such joints provides flange members having unthreaded central openings adapted for sliding disposition about and welding to the respective pipe ends. With each of these types of joint forming apparatus, a resilient sealing gasket ring or the like is utilized between the flange members. A third type of apparatus for forming such joints utilizes a pair of annular flange members relatively tightly slidable on the pipe ends to be joined, the two flanges being adapted to cooperatively define an annular recess at the pipe ends in which is received a compatibly shaped annular sealing gasket and utilizing a bolt arrangement or the like to draw the flanges axially together to compress the gasket therebetween and against the pipe ends. An example of this type of apparatus and a pipe joint formed therewith is disclosed in Canadian Pat. No. 651,118, issued Oct. 30, 1962, to Robert H. Edmonds.
Pipe joints of the above described types are relatively tight, allow considerable deflection and are relatively simple and inexpensive to install, especially joints formed with the latter above-identified type of apparatus. As a result, they are used effectively in pipelines in gas and water conveying systems. However, as those skilled in the art are aware, pipes of a variety of different materials, e.g., cast iron and ductile iron, are conventionally utilized in such systems and have different outer diametric dimensions for pipes of the same inner diameter size because of the different wall thickness required for different materials. Therefore, with any of the above three types of conventional joint-forming apparatus, differently sized flange members must be utilized for each different type and size pipe in order to avoid undesirable gaps between the flange and the pipe ends, which would render welding and threading connection impractical. Accordingly, a considerable inventory of differing flange members must normally be maintained. Moreover, with particular regard to the third above-identified type of joint-forming apparatus, it will be understood that the two pipes in the joint formed between the ends thereof are held together by the gripping force of the sealing gasket exerted against the gasket by the flanges utilized in combination with set screws extending generally radially through the flanges into engagement with the surface of the pipe ends and, therefore, such joints would be susceptible to failure under high operating pressures were a single size flange used with pipes of different wall thickness that would result in gaps in some instances that would make it difficult to form an effectively strong joint that would withstand high pressures. In this type of prior apparatus, it should also be noted that the set screws have no effect upon the gripping force exerted through the gasket directly at the pipe ends.
In contrast, the present invention provides a new and improved pipe joint and apparatus therefor of the third above-identified type specially adapted to exert significantly increased gripping force through the gasket thereof directly radially inwardly against the pipe ends joined and sealed thereby, the joint-forming apparatus being further adapted for use with pipes of differing materials and outer diameters.